Monahans is located at 31°35'38" North, 102°53'30" West (31.593889, -102.891944).

According to the United States Census Bureau, the city has a total area of 24.82 mi2 (64.29 km2). 24.81 mi2 (64.25 km2) of it is land and 0.01 mi2 (0.03 km2) of it is covered by water. The total area is 0.05% water.

Monahans is located in the Central Standard Time (CST) timezone, GMT-06:00. It observes Daylight Saving Time (DST).